1. Field of Invention
This invention relates generally to retention systems for protective helmets and more particularly, to improvements in retention systems utilized for bicycle helmets.
2. Description of Prior Art
Protective helmets are widely used in industry and sporting activities as hard hats, crash helmets, ski helmets, bicycle helmets, and the like. Such helmets comprise a protective body designed to distribute the load of any localized impact over a larger area. The helmet is supported by the head of the wearer during use. Various helmet retention systems have been devised to provide comfort and fit to the wearer while continuing to provide the desired protection.
Helmet retention systems designed for use with bicycle helmets should have the following characteristics:
(a) The means to retain the helmet on the wearer's head during an impact to the helmet from any direction, front, rear, sides, or top, that may result from a crash while operating a bicycle.
(b) The means to hold the helmet on the wearer's head in the proper horizontal position, covering the forehead, for maximum crash protection.
(c) The means to hold the helmet securely on the wearer's head so the helmet is stable and does not shift and slide on the head during normal movement involved with cycling.
(d) System should be fully adjustable to fit varying head sizes within a selected range.
(e) System should be fully adjustable to engage the wearers head in a preferred position.
(f) System should provide good wearer fit and comfort while cycling.
One type of helmet retention system that contains many of these characteristics is a system incorporating an adjustable headband. A typical "Hard Hat" retention system disclosed in Erlendson U.S. Pat. No. 4,263,679, 4/28/81 incorporates a generally horizontal adjustable headband with an attached rear band that engages the nape area of the user's head. Another similar design by Daly U.S. Pat. No. 4,051,555, 10/4/77 incorporates an adjustable headband where the rear portion of the headband slopes downward to engage the nape area of the wearer's head.
These designs provide good fit, stability, and comfort for the wearer while holding the helmet in its proper horizontal position. However, these types of helmet retention systems would not provide adequate protection from the substantial impacts associated with a bicycle crash. These helmet retention systems do not provide helmet retaining straps secured under the wearer's chin and consequently can be dislodged from the wearer's head during a crash.
Dye U.S. Pat. No. 2,846,683, Oct. 12, 1956 discloses an improved helmet retention system which utilizes a headband with the addition of helmet retaining straps secured under the wearer's chin. This type of retention system will securely hold the helmet on the wearer's head during a crash. The system will also provide the wearer with good helmet fit, stability, and comfort. However, the design's lack of an impact absorbing body and the complexity of its headband, and support system would make it difficult to use in a bicycle helmet retention system.
Present day bicycle helmet designs like those disclosed in Broersma U.S. Pat. No. 4,901,373, 2/20/90 and Broersma U.S. Pat. No. 4,903,348, 2/27/90 consist of a dome shaped helmet body made from an impact absorbing material, typically molded from expanded polystyrene. The helmet body has inner and outer surfaces. Openings through the front and rear of the body allow retention straps to pass through. Helmet retention is accomplished by retention straps passing across the outer surface of the helmet body then extending down through the openings in the body. The retention straps continue down the sides of the wearer's head and are joined under the chin with a buckle.
Since the helmet body's inner surface is larger than the wearer's head; foam cushion pads are used on the top, and lower rim of the inner surface of the helmet body to seat the helmet on the head of the wearer. The foam cushion pads provide comfort, fit, and helmet stability for the wearer.
It is important to note that these foam cushion pads are utilized for stability, comfort, and fit only; they play a very small part in the impact absorbing characteristics of a bicycle helmet. Bicycle helmet manufacturers generally provide several sets of foam cushion pads in various thicknesses to allow one size of helmet body to fit several different head sizes. This method has several disadvantages:
(a) When the size difference between the helmet body's inner surface and the wearer's head is large; thick foam cushion pads must be used to properly seat the helmet on the wearer's head. The use of thick pads can flex and compress, degrading helmet fit and stability. This is a common problem for users whose head size falls in between standard ( small, medium, and large ) helmet sizes.
(b) Typically, a limited number of foam cushion pads are placed around the lower rim of the inner surface of the helmet body to contact the wearer's head. This limited number of pads must support the weight of the helmet, and forces from the retention straps; causing uncomfortable "pressure points" around the wearer's head.
(c) The foam cushion pads of the helmet contact the wearer's head in a generally horizontal, annular contact area, set just above the ears. This is not a natural position for head wear to sit on the head. Novice cyclists tend to wear their bicycle helmet in a more natural inclined position, higher up on the forehead. However, this position degrades the helmet's ability to protect the wearer's forehead.